A mass spectrometer system for the precise comparison of the isotope ratio of sulfur, carbon and oxygen is described. The results of 34S/32S ratio measurements indicate the reproducibility is better than ±0.2per mil in terms of δ34S scale. δ34Stroilite of a standard sulfur of the Canadian group was found by our system to be +11.2 per mil, comparing +10.8 per mil, the average given by the group.
